东北黑土氮素转化和酶活性对水热条件变化的响应

发布时间：2018-03-12 23:36

本文选题：黑土　切入点：干湿交替　出处：《东北师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：东北黑土区位于温带半湿润季风气候区,其气候特点是冬季寒冷干燥、夏季雨热同期。在长达半年的冬春季节里,土壤处于冻结和解冻状态,存在明显的季节性冻融现象;而夏季雨热同期导致农田土壤湿度变化频繁,干湿交替现象普遍存在。冻融和干湿交替过程是黑土区土壤中氮素迁移转化的重要外营力之一,也是黑土区土壤物质流和能量流变化的重要驱动力。本论文以东北黑土区黑土为研究对象,采用室内模拟试验的方法,研究不同湿度、不同频度干湿交替过程以及长期自然冻融和短期频繁冻融作用对土壤氮素转化及土壤酶活性的影响,初步揭示2种水热条件变化对土壤氮素转化影响的微观作用机理。研究结果如下:1、含水量的影响。在相同培养时间,含水量为20%土壤的铵态氮和硝态氮含量低于含水量为35%和60%的土壤,而氮素转化速率则随着土壤含水量的增加而增加,且随着培养时间的延长,氨化、矿化及硝化速率均呈下降趋势;随着培养时间的增加,脲酶活性呈大幅度变化后波动性变化的趋势,转化酶活性呈现波动性变化,但不同含水量对土壤脲酶和转化酶活性的影响差异不显著。2、干湿交替的影响。在培养期间,对照组与处理组土壤铵态氮及硝态氮含量整体呈下降趋势,但与对照组相比较,干湿交替作用促进了铵态氮和硝态氮含量的增加;经历干湿循环的实验组氮素转化速率整体上高于恒定含水量的对照组,且随着培养周期的增加,氮素转化速率先大幅度下降,随后呈波动性变化;受土壤含水量和干湿循环的影响,除了第0.5、3周期实验组脲酶活性低于对照组外,剩余培养周期里的脲酶活性均表现为:实验组对照组;转化酶活性也表现出相同的变化规律(8周期除外)。3、短期冻融的影响。整个培养期间,冻融作用下的土壤铵态氮和硝态氮含量随着培养时间的增加而增加。除了培养1周期内低强度冻融(-10—5℃)的土壤铵态氮含量最低外,剩余培养周期里,铵态氮含量均表现为低强度冻融(-10—5℃)高强度冻融(-25—5℃)对照组(5℃),不同冻融温度作用下硝态氮含量差异明显。与对照组相比较,冻融交替降低了土壤的矿化速率和硝化速率,提高了土壤的氨化速率,氮素转化速率对不同强度冻融响应显著,总体上看,土壤氨化速率表现为:低强度冻融高强度冻融对照组。受土壤温度和冻融交替的影响,土壤脲酶活性和转化酶活性均低于对照组,且两种酶活性均表现为低强度冻融高强度冻融(1周期除外)。4、长期冻融的影响。长期自然冻融有利于铵态氮含量的积累,而硝态氮含量表现为下降趋势。随着冻融时间的增加,土壤氨化速率和矿化速率表现为相似的增长趋势,而土壤硝化速率在整个室外冻融期间表现为负增加。和对照土壤相比较,含水量较高的3号平行样品的土壤脲酶活性和转化酶活性有一定的提高,其余两个平行样品的土壤脲酶活性和转化酶活性均有不同程度的下降。5、懫用Pearson的双因素相关性分析得到,除了在不同含水量状况下,其与铵态氮相关性不显著,短期冻融处理下,其与矿化速率相关性较差外,土壤中氮素转化的相关指标与脲酶活性均有显著相关性。而转化酶活性除了在干湿交替状况下与氮素转化的相关指标相关性不显著外,不同含水量及冻融交替作用下的土壤氮素转化速率和冻融循环的无机氮(铵态氮、硝态氮)与转化酶活性的相关性均较好。综上,干湿交替和冻融交替两种水热条件变化对土壤氮素转化和土壤酶活性均有重要影响。
[Abstract]:The black soil region of Northeast China is located in the temperate semi humid monsoon climate zone, its climate is cold and dry in winter, hot summer rain period. In over half of the winter season, the soil in freezing and thawing condition, there are obvious seasonal freeze-thaw phenomenon; summer rain heat over the same period in the farmland soil moisture changes frequently, the phenomenon of the wet dry freeze thawing process. Alternate nitrogen in black soil area in migration is one of the important forces of transformation, is also an important driving force of soil material and energy flow of change. The black soil region of Northeast China as the research object, using the method of indoor simulation experiment, study different humidity, different frequency and alternate process the long-term natural freeze-thaw and frequent short-term effects of freezing and thawing on soil nitrogen transformation and soil enzyme activity, revealed 2 hydrothermal conditions on soil nitrogen transformation The micro mechanism of the influence. The results are as follows: 1. The influence of water content. At the same time of culture, 20% moisture content of soil ammonium nitrogen and nitrate nitrogen content is lower than the water content is 35% and 60% of the soil, and nitrogen conversion rate will increase with the increase of soil moisture, and with the culture time the extension, ammonification, mineralization and nitrification rate decreased; with the increase of culture time, the urease activity showed a significant change after the volatility change trend, the invertase activity showed fluctuation, but the effect of water content on soil urease and invertase activity had no significant difference.2, influence of wetting. During the incubation period, the control group and the group of soil ammonium nitrogen and nitrate nitrogen content decreased, but compared with the control group, wet dry alternation promotes the increase of ammonium nitrogen and nitrate nitrogen content; dry wet cycle real experience The experimental group on the whole nitrogen conversion rate was higher than that of the control group with constant water content, and with the increase of the culture cycle, nitrogen transformation rate first decreased, then fluctuated; affected by soil moisture and the effect of dry wet cycle, but lower than that in group 0.5,3 the urease activity cycle in the control group, the remaining urease activity cycle. The training are as follows: the experimental group control group; invertase activity also showed the same variation (8 cycles except).3, the short-term effects of freezing and thawing. During the whole incubation period, freezing and thawing of soil ammonium nitrogen and nitrate nitrogen content increased with incubation time. In addition to training cycle 1 in low intensity freeze-thaw (-10 - 5 DEG C) the soil ammonium nitrogen content was the lowest, the remaining period of cultivation, the content of ammonium nitrogen showed low intensity freeze-thaw (-10 - 5 DEG C) high strength and freeze-thaw (-25 - 5 DEG C) and control group (5 C), different freeze-thaw temperature With the content of nitrate nitrogen significantly. Compared with the control group, alternate freezing and thawing reduced mineralization rate and nitrification rate of the soil, improve the soil ammonification rate, nitrogen transformation rate of different intensity freeze-thaw response significantly, on the whole, the soil ammonification rate as follows: freeze-thaw control group low intensity freeze-thaw high strength. Affected by soil temperature and freezing thawing effect, urease activity and invertase activity in soil were lower than the control group, and the two enzyme activities were low intensity freeze-thaw high strength (1 freeze-thaw cycle except.4), the long-term effects of freezing and thawing. The long-term natural freeze-thaw is conducive to ammonium nitrogen content the accumulation, and the nitrate nitrogen content was decreased. With the increase of freezing thawing time, soil ammonification rate and mineralization rate showed a similar trend, while the soil nitrification rate during freezing thawing showed a negative increase in the outdoor and compared to control soil, The soil urease activity and invertase activity of high moisture content of the 3 parallel samples has been improved to a certain extent, the remaining two parallel samples were the soil urease activity and invertase activity decreased.5, Zhi with two factor Pearson correlation analysis, except in different moisture conditions, and ammonium nitrogen the correlation is not significant, short-term freeze-thaw treatment, the mineralization rate and poor correlation, correlation index of nitrogen transformation and soil urease activity had significant correlation. The invertase activity in addition to no significant correlation in the condition of relevant indicators under the dry wet alternate with nitrogen transformation, different water content and freeze-thaw cycles under the action of the soil nitrogen conversion rate and freezing thawing cycle of inorganic nitrogen (ammonium and nitrate) correlation with invertase activity was obtained. To sum up, and freezing and thawing cycles of two kinds of water and heat conditions change on the wet dry Soil nitrogen transformation and soil enzyme activity have important effects.

【学位授予单位】：东北师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S155.27

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